Thought I'd share this find with all the wonderful folks here. :-)
The incredible sounds you can download here http://virtualplaying.com/virtual-playing-orchestra/
contain a wealth of exquisitely sampled instruments that sound infinitely better than those that come with the free Sforzando player and contain dozens more instruments.
Perhaps the best part yet is that they come in .SFZ format and can be dropped right into the player you already have!
After you download, unzip the file, open each directory (e.g. strings, woodwinds, etc.) select the files with .sfz extensions, and drag-drop them as shown in the screenshot.
P.S. If you get an error message (I forget what it says, make sure that none of the files selected to drop into Sforzando have non-supported extensions).
After this is done, in order to access the sounds choose the newly added "user" option which will appear in the tab below the BiaB and Tablewarp. (see additional screenshot)